Apparatus and method for deployment of an endoluminal device

ABSTRACT

An introducer deploys an endoluminal device in a distal location from a proximal location. The introducer comprises a retrograde portion, an anterograde portion axially moveable relative to the retrograde portion, a shaft having a distal tip and an anterograde sheath attached to the distal tip, and an inflatable balloon mounted radially outside the retrograde portion for anchoring the device during deployment from its proximal end to its distal end. The retrograde portion may comprise bilumen tubing having an external wall, an internal wall that defines a central lumen radially inward of the internal wall, and an annular lumen in fluid communication with the balloon defined between the external wall and the internal wall.

TECHNICAL FIELD

This invention relates generally to endoluminal devices and, morespecifically, to methods and apparatus for deploying endoluminal devicesin body lumens.

BACKGROUND OF THE INVENTION

A stent is an elongated device used to support an intraluminal wall. Inthe case of a stenosis, a stent provides an unobstructed conduit througha body lumen in the area of the stenosis. Such a stent may also have aprosthetic graft layer of fabric or covering lining the inside and/oroutside thereof. Such a covered stent is commonly referred to in the artas an intraluminal prosthesis, an endoluminal or endovascular graft(EVG), or a stent-graft. A stent-graft may be used, for example, totreat a vascular aneurysm by removing the pressure on a weakened part ofan artery so as to reduce the risk of rupture. Other devices, such asfilters, particularly vena cava filters, may have similar structures tostents and may be placed in a body lumen by similar methods. As usedherein, the term “endoluminal device” refers to covered and uncoveredstents, filters, and any other device that may be placed in a lumen. Theterm “stent” as used herein is a shorthand reference referring to acovered or uncovered stent.

Typically, an endoluminal device, such as a stent-graft deployed in ablood vessel at the site of a stenosis or aneurysm, is implantedendoluminally, i.e. by so-called “minimally invasive techniques” inwhich the device, restrained in a radially compressed configuration by asheath or catheter, is delivered by a delivery system or “introducer” tothe site where it is required. The introducer may enter the body from anaccess location outside the body, such as through the patient's skin, orby a “cut down” technique in which the entry blood vessel is exposed byminor surgical means. The term “proximal” as used herein refers toportions of the stent or delivery system relatively closer to thisaccess location, whereas the term “distal” is used to refer to portionsfarther from the access location.

When the introducer has been threaded into the body lumen to the stentdeployment location, the introducer is manipulated to cause the stent tobe ejected from the surrounding sheath or catheter in which it isrestrained (or alternatively the surrounding sheath or catheter isretracted from the stent), whereupon the stent expands to apredetermined diameter at the deployment location, and the introducer iswithdrawn. Stent expansion may be effected by spring elasticity, balloonexpansion, or by the self-expansion of a thermally or stress-inducedreturn of a memory material to a pre-conditioned expanded configuration.

Referring now to a typical prior art introducer as seen in FIGS. 1A and1B, there is shown a standard pre-loaded delivery system 10 comprisingan outer sheath 12, a compressed endoluminal device 14 loaded therein,and a conventional stabilizer 16 loaded adjacent to the proximal end 17of the endoluminal device. A standard deployment technique comprisesmaneuvering the introducer to a desired deployment location andretracting outer sheath 12 so that the endoluminal device is deployedbeginning at its distal end and ending at its proximal end. Stabilizer16 stabilizes or prevents retraction of endoluminal device 14 whensheath 12 is retracted, thus effecting deployment of the device into adesired location by forcing relative movement between the sheath and thedevice.

Delivery system 10 also may comprise a catheter tip 20 at its distal endattached to an internal shaft 23 that runs through the delivery systemthrough inner lumen 22 in stabilizer 16, as shown in FIG. 1A. Astabilizer handle 26 is typically located at the proximal end ofstabilizer 16, outside the body lumen. Internal shaft 23 may guide thedelivery system through the body lumen over a guidewire (not shown) tothe area to be repaired, or may be adapted for inflating a balloon (ifapplicable), and/or for flushing the system.

It is often important during endoluminal device delivery to ensureaccurate placement of the device termini, particularly in intravasculardeployment of multipart stents. Improper stent placement can preventsuccessful medical treatment. There is a particular need in the art toanchor the proximal end of a self-expanding stent while deploying thedistal end, and also to provide accurate deployment of self-expandingstents in a way that prevents recoil of the endoluminal device uponrelease, which may adversely affect the accuracy of the deviceplacement.

In a procedure to repair an abdominal aortic aneurysm (AAA), use of amodular self-expanding stent involves accurate placement of a terminusof a first stent component in the abdominal aorta just below the renalarteries. A second stent component is then deployed in the first stentcomponent and permitted to extend to a terminus in one of the iliacarteries. It is difficult, however, to ensure accurate placement of theiliac terminus of the second stent component. If the terminus is notplaced far enough into the iliac, then the stent may be ineffective. Ifthe terminus extends too far, it may interfere with blood flow inarteries branching from the iliac, such as the internal iliac artery.This problem also occurs in the deployment of multipart stents in otherbranched arteries. Thus, it is particularly desirable to provide a wayto ensure accurate deployment of all the termini of a multipart stent.

SUMMARY OF THE INVENTION

In accordance with this invention, there is provided an introducerhaving a retrograde portion and an anterograde portion axially moveablerelative to one another. An inflatable balloon is provided radiallyoutside the distal end of the retrograde portion, such as for anchoringthe endoluminal device during deployment of the endoluminal device fromthe device proximal end to the device distal end. The anterogradeportion comprises a distal tip and an anterograde sheath attachedproximally to the distal tip. A shaft is attached to the distal tip andextends concentrically through a central lumen defined by theanterograde portion and retrograde portion, such as for moving theanterograde portion relative to the retrograde portion. The endoluminaldevice is mounted concentrically over the shaft in the central lumen andhas a distal end contained by the anterograde portion and a proximal endcontained by the retrograde portion.

The retrograde portion may comprise bitumen tubing having an externalwall, an internal wall that defines the central lumen radially inward ofthe internal wall, and an annular lumen defined between the externalwall and the internal wall. The annular lumen is in fluid communicationwith the balloon, which is located radially outward of the external wallat or near a distal end of the retrograde portion.

The invention also comprises a method for deployment of an endoluminaldevice in a distal location in a body lumen from a proximal location.The method comprises the steps of inserting an introducer of the presentinvention into a body lumen, aligning the proximal end of theendoluminal device in a deployment location, and retracting theretrograde portion to deploy the proximal portion of the endoluminaldevice including the proximal end. The retrograde portion of theintroducer is then advanced so that the inflatable balloon is alignedaxially within the proximal portion of the endoluminal device. Theballoon is inflated to compress the endoluminal device against the lumenwall while the shaft is extended to distally advance the anterogradesheath to deploy a remaining portion of the endoluminal device.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but not restrictive,of the invention.

BRIEF DESCRIPTION OF THE DRAWING

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing, in which:

FIG. 1A shows a longitudinal section of a standard introducer of theprior art;

FIG. 1B shows a detailed longitudinal section of the encircled portionof FIG. 1A.;

FIG. 2A shows a longitudinal section of an exemplary introducer of thepresent invention;

FIG. 2B shows a longitudinal section of the introducer of FIG. 2A inmid-deployment of an endoluminal device;

FIG. 2C shows a longitudinal section of the introducer of FIG. 2A afterdeployment of the endoluminal device; and

FIG. 3 depicts a flowchart of an exemplary method of deploying anendoluminal device using the introducer of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will next be illustrated with reference to the figureswherein the same numbers indicate similar elements in all figures. Suchfigures are intended to be illustrative rather than limiting and areincluded herewith to facilitate the explanation of the apparatus of thepresent invention.

Referring now to FIGS. 2A–C there is shown an exemplary introducerembodiment 200 in accordance with the present invention. Retrogradeportion 202 of introducer 200 comprises bitumen tubing having anexterior wall 203, an interior wall 205, an annular lumen 208 defined bythe space between the interior wall and the exterior wall, and a centrallumen 210 radially inward of the interior wall. Balloon 212 is locatedat or near the distal end of exterior wall in fluid communication withannular lumen 208, allowing fluid to flow through the annular lumen toinflate the balloon when desired. Anterograde portion 204 of introducer200 is attached to shaft 206 and comprises distal tip 224 attached toanterograde sheath 226, which further defines an anterograde portion ofcentral lumen 210. Shaft 206 may have one or more radiopaque markers228, one shown in FIG. 2A adjacent the proximal end 231 and anothershown adjacent the distal end 232 of the endoluminal device 230, whichis contained within central lumen 210.

An exemplary method for using introducer 200 is depicted in theflowchart shown in FIG. 3. The method may be performed, for example, inan operating room or an angiographic suite, preferably underfluoroscopic guidance as is known in the art. First, introducer 200 isinserted into a body lumen 240, as indicated in step 310, distal tip 224first, from a proximal access site (not shown), such as a femoral arteryor iliac artery for vascular deployment. Typically, introducer 200 isthreaded into the lumen over a guidewire (not shown) as is well known inthe art. The access site may be surgically exposed and punctured with,for example, an 18-gauge needle as is known in the art.

Next, in step 320, the proximal end 231 of endoluminal device 230 isaligned in an appropriate deployment position. Fluoroscopic guidance,such as by using radiopaque markers 228 and/or a guide wire, may be usedto guide proximal end 231 into the desired position. For example, whereendoluminal device 230 is an AAA stent graft, proximal end 231 of device230 is positioned in the iliac (not shown) artery, preferably just abovea branch of the internal iliac artery (not shown). Although illustratedherein with respect to a self-expanding stent, the endoluminal devicemay comprise any device for placement in a lumen, including but notlimited to stents, grafts, combinations thereof, and filters, such asvena cava filters.

After end 231 is aligned in the desired position, retrograde sheath 202is retracted in the direction of arrow A as shown in FIG. 2B, at leastfar enough to expose proximal section 231 of device 230, allowing it toexpand against the lumen wall 242, as indicated in step 330. Then,retrograde portion 202 is advanced in the direction of arrow B so thatballoon 212 is aligned under proximal section 231 of device 230, asindicated in step 335 and as shown in FIG. 2C. Balloon 212 is inflatedin step 340, by pressurizing the balloon with fluid communicated throughannular lumen 208, to exert radial force that presses the proximalsection 231 of device 230 against the lumen wall 242.

In step 350, shaft 206 is extended distally to advance anterogradeportion 204 of introducer 200 to deploy anterograde portion 235 ofdevice 230 as shown in FIG. 2C. As used herein, the “retrograde portion”of device 230 refers to any portion initially covered by the retrogradesheath, and the “anterograde portion” of device 230 refers to theremainder of the device distal of the retrograde portion. Prior toextending the shaft, the guidewire and retrograde portion 202 ofintroducer 200 may typically be locked together to prevent movement ofthe retrograde sheath or the guidewire during extension of the shaft.After anterograde portion 235 has been deployed, balloon 212 is thendeflated as indicated in step 360, anterograde portion 204 andretrograde portion 202 brought together again abutting one another, andintroducer 200 removed from the lumen in accordance with step 370. Ifdesired, prior to removal from the lumen, balloon 212 may be used formodeling device 230 to better conform to the contours of the lumen wall242, as is known in the art. Thus, introducer 200 and the methoddepicted in FIG. 3 provides means for accurately placing the proximalend of an endoluminal device.

Although depicted in FIGS. 2A–2C with the anterograde portion 204 andretrograde portion 202 extending approximately equally over the lengthof device 230, in many embodiments the length of the anterograde portionover the device is longer than the length of the retrograde portion overthe device. Retrograde portion 202 may typically only be long enough sothat when proximal end 231 of device 230 is deployed by retractingretrograde portion 202, the deployed length of the device proximal endis sufficient to be engaged by balloon 212 against body lumen 242.

One concern of the reverse deployment method and introducers describedherein for deployment of AAA stent-grafts, is that if anterogradeportion 204 is too long, the anterograde portion may enter the heartduring the advancement step. Other, non-AAA applications may havesimilar concerns with surrounding organs or other body structure. Thus,the dimensions of the introducer may be optimized to prevent damagecaused by anterograde portion 204 being too long. One way of shorteninganterograde portion 204 for a particular application is to lengthenretrograde portion 202. Thus, in some embodiments, retrograde portion202 may be longer than just an effective amount to provide asufficiently long deployed proximal portion 231 of device 230 forengagement by balloon 212, including embodiments where anterogradeportion 204 and the retrograde portion are equal, or where theanterograde portion is longer than the retrograde portion. Embodimentshaving retrograde and anterograde portions of approximately equal lengthmay be useful where the location of the proximal end of the device isless important than aligning the middle of the device with a certainregion of a lumen.

Although depicted herein with a retrograde portion comprising coaxialbilumen tubing, the introducer of the present invention may compriseother structures that provide a balloon radially outside the retrogradeportion. For example, the bitumen tubing may not comprise coaxialtubing, but rather tubing wherein the central lumen and the lumen influid communication with the balloon are side-by-side or in some otherconfiguration. The longitudinal sectional view of such a configurationwould be similar to FIG. 2A except that the upper longitudinal sectionof lumen 108 would be the entire lumen and there would be no bottomsection of that lumen. Other embodiments may also be provided within thescope of this invention.

Although illustrated and described herein with reference to certainspecific embodiments, the present invention is nevertheless not intendedto be limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the spirit of the invention.

1. An introducer for deployment of an endoluminal device in a distallocation inside a body lumen from a proximal location outside the bodylumen, the introducer comprising: a retrograde portion; an anterogradeportion, axially moveable relative to the retrograde portion, comprisinga distal tip and an anterograde sheath attached proximally to the distaltip; a shaft attached to the distal tip and extending concentricallythrough a central lumen defined by the anterograde portion andretrograde portion; an endoluminal device mounted concentrically overthe shaft in the central lumen and having a distal end contained by theanterograde portion and a proximal end contained by the retrogradeportion positioned radially outward of the proximal end of the device;and an inflatable balloon mounted radially outside the retrogradeportion, the balloon positioned to anchor a proximal portion of theendoluminal device against the body lumen during deployment of thedevice.
 2. The introducer of claim 1, wherein the retrograde portioncomprises bilumen tubing having an external wall, an internal wall thatdefines the central lumen radially inward of the internal wall, and anannular lumen defined between the external wall and the internal wall,the annular lumen in fluid communication with the balloon, the balloonlocated radially outward of the external wall at or near a distal end ofthe retrograde portion.
 3. The introducer of claim 1, wherein theendoluminal device has a length and the balloon has a length that isless than the endoluminal device length.
 4. The introducer of claim 1,wherein the retrograde sheath and the anterograde portion axially abutone another.
 5. The introducer of claim 1, wherein the retrogradeportion extends over a longer portion of the endoluminal device than theanterograde sheath.
 6. The introducer of claim 1, wherein theanterograde sheath extends over a longer portion of the endoluminaldevice than the retrograde portion.
 7. The introducer of claim 1,wherein the anterograde sheath and the retrograde portion extend overessentially equal lengths of the endoluminal device.
 8. The introducerof claim 1, wherein the shaft comprises one or more radiopaque markers.9. The introducer of claim 1 further comprising at least a firstradiopaque marker that marks the proximal end of the device.
 10. Theintroducer of claim 9 further comprising a second radiopaque marker thatmarks the distal end of the device.
 11. The introducer of claim 1,wherein the endoluminal device comprises a stent, graft, or acombination thereof.
 12. The introducer of claim 1, wherein theendoluminal device comprises a vena cava filter.
 13. The introducer ofclaim 1, wherein the endoluminal device comprises a stent-graft forrepair of an abdominal aortic aneurysm.
 14. The introducer of claim 1,wherein the endoluminal device is self-expanding.
 15. The introducer ofclaim 1, wherein the endoluminal device is adapted for deployment in alocation having a sensitive area located distally of the deploymentlocation, the anterograde portion having a length sufficiently short toprevent intrusion of the anterograde portion into the sensitive area.16. An introducer for deployment of a self-expanding endoluminal devicein a distal location inside a body lumen from a proximal locationoutside the body lumen, the introducer comprising: a retrograde portionhaving a distal end and comprising coaxial bilumen tubing having anexternal wall, an internal wall, a balloon located radially outward ofthe external wall at or near the retrograde portion distal end foranchoring the endoluminal device against the body lumen duringdeployment of the device from the device proximal end to the devicedistal end, a retrograde central lumen defined radially inward of theinternal wall, and an annular lumen defined between the external walland the internal wall, the annular lumen in fluid communication with theballoon; an anterograde portion comprising a distal tip, an anterogradesheath attached proximally to the distal tip, and an anterograde centrallumen defined radially inward of the anterograde sheath; an endoluminaldevice mounted concentrically over the shaft in the retrograde andanterograde central lumens, the device distal end contained by theanterograde portion and the device proximal end contained by theretrograde portion, the retrograde portion having a length sufficient tobe engaged by the balloon against the lumen wall; and a shaft attachedto the distal tip and extending concentrically through the anterogradeand retrograde central lumens, the shaft comprising at least a firstradiopaque marker that marks the proximal end of the endoluminal deviceand adapted for moving the anterograde portion relative to theretrograde portion.